Sealed package and method of making same



Feb. 8, 1944. e. HOUSEHOLDER ETAL 2,341,379

7 SEALED PACKAGE AND METHOD OF MAKING SAME Filed April8, 1940 Llczusa NmOOO PASTEURIZED D nmpmw t: E wmkzu N0 R wmm+m J 0 wmvfA um m7 FL M a Patented Feb; 8, 1944 SEALED PACKAGE AND METHOD or 4 MAKING SAME I V Garrison Householder, S

outh Hadley Center, and

'Walter V. Shearer, West Springfield, Mass., assignors to The Plastic Coating Corporation,

Holyoke, Mass., a corporation of Massachusetts g 1 I Application April 8, 1940, Serial No. 328,492

""4 Claims. (craze-5.5)

This invention relates to the bonding or securing of sheets or strips of paper or the like to wax coated surfaces in general, and to the application .of over-caps to wax coated cardboard containers in particular. I

Many States and municipalities have regulations governing the distributionoi milk which include the requirement that the tops of the containers shall be overcapped to protect the discharge opening and the adjacent surface of the container against contamination.- In some cases it is also required that the container carry the date of production of the milk contained therein or the date of its pasteurization. The grade or the milk and other information is also sometimes printed'or otherwise stamped on the top of the container. It is highly desirable and sometimes required, that in addition to its sanitary function the over-cap serve as a tamper-proof seal preventing re-use of the container or its redating. This requires that the over-cap shall be so attached to the container that it cannot be removed without destruction or the over-cap.

. It has been customary to stamp the date or other indicia on thetop oithe container and apply an over-cap of transparent or semi-transparent material heat sealed to the container by means of the wax coating of the container or by the addition of a wax coating to the over-cap or the use of a wax solvent. Such methods have been unsatisfactory because a wax held cap is easily peeled from the container and can be easily resealed. .-It is one objectof waterproof tamper-proof bond between a wax the invention to secure a coated container and a sheet or strip 01 paper, or the like, which serves as a protecting cover or sealior the container.

Other and further objects broadly relating to the character of-the bond; and the means by which it is obtained will bemade apparent in the followings-specification and claims. I

In the accompanying drawing,

Fig. 1 is a perspective view of vided with an over-cap in accordance with this invention; a

Fig. 2 is a sectional view, on an enlarged scale, taken substantially on line 2-2 of Fig. 1;

Fig. 3 is a plan view of one form of over-cap; and

Figs. 4 and 5 are fragmentary perspective views, similar to Fig. 1, showing diflerent types of seal.

Referring to the drawing, It indicates a cardboard container such as is used for distributing milk. Such containers are formed of heavy paper a container proor bristol board which has been coated on both the inside and outside with a relatively heavy coating of wax, such this kind may be variouslyconstructed. The form shown in Figs. 1 and 2 of the drawing :comprises a tubular body ll, the'end'edges of which are crimped about rectangular end pieces, the top end piece being shown at l2 in Fig. 2 and the crimped connection of the tubular body'to the top being indicated at it. The wax coatings of the at H. The coatings i4 render the container fluid tight. The topoi-the container is provided adjacent one corner with a filling and discharge opening which isflciosed by a closure, indicated in dotted line at ,l5,in Fig. 1,

which is sealed in place with wax.

Over the top of the container we apply an overcap generally indicated at I! which extends around and beneath the flanged top of a the container and is heat sealed to the under side of the flange or the adjacent portion ofthe wall of the container.

This over-cap is formed or a sheet of paper or the like 20, the under side of which is provided with a coating of thermoplastic material which has the property of adhering to paper but which is immiscible or non-compatible with wax. Various plastic and resinous, materials have this property to a degree and may be used in carrying out our invention, but we have'found that the group of cornproteins constituting theaqueous-alcoholsoluble prolamines, or zein have properties which .are of particular advantage for our purposes and this material is used in the coating compositions employed by us in the preferred form of our invention.

nesses oi the various elements have been shown exaggerated and out of proportion for the sake of clearness.

In applying the cap heat and pressure are simultaneously.applied tothe edge of the cap where 'it is to be sealedto the container. This may be done by any suitable mechanism having a heated pressing member. The heat applied is sufficient to soften and permit flowage of the wax coating or the container and at the same time render the zein coating of the over-cap tacky.

The so softened wax and zein being incompatible and immiscible, preserve their identity and the pressure applied is sufllcient to cause the coated over-cap to push aside the wax coating of the conas paraflln. Containers of,

In Fig. 2 the paper 20 of the over-cap is shown provided on its under side with a relatively tainer and bring the zein coating of the over-cap into direct contact with the surface of the container material ll. Upon removal of the heat and pressure the zein coating bonds the paper stock of the over-cap directly to the paper or bristol board stock of the container, as shown at 23 in Fig. 2.

The bond afforded by the zein is suiiiciently strong so that the over-cap cannot be removed without destruction of the cap. Milk spilled over the top of the container does not prevent the proper bonding of the overcap to the container. A further advantage is found in the factthat zein. is an odorless, and tasteless corn derivative wholly unobjectionable for use in connection with food packages.

The over-cap may be provided with printing such as arrows 24, Fig. 3, to indicate the position of the underlying closure, and any other printed matter such as indicated at 25 may also be applied.

While we have described our invention as specifically applied to an over-cap covering the entire top of a container, its structural advantages are also realized in many other uses. For example, simply as a seal, as shown in Fig. 4 where a wide sealing strip 26 is placed over the closure "21 of a wax coated package 28, or, as shown in .Fig. 5. it may take the form of a narrow tape 29 ,heat sealed around the pleats of a wax coated cap 30 applied over the mouth of a glass bottle. As illustrating a typical coating formula for our purposes we give the following: 1

Parts Zein 30 Plasticizer 7V Gum rosin 22 Solvent 87 The amount of zein employed may be varied rather widely in connection with the other in- ,gredients of the compositionfrom'5 to 50 parts of, zein being usable depending on, the character and amount of the other ingredients.

"The plasticizer lowers the softening temperatures of. the zein and resins, increases flexibility, decreases brittleness and increases tackiness.

'The amount of plasticizer can be varied over a wide range, the upper limit being determined by the point at which the coating does not dry sufficiently tack free. Under some circumstances where increased brittleness would not be a serious factor the plasticizer could be omitted. Glycerine, 'di-ethylene glycol, and tri-ethylene glycol is 80-95% ethyl alcohol, the balance water. The composition will tolerate small amounts of other solvents and denaturants. Any other solvent composition which will. dissolve the mixture may be used. The amount of solvent used will depend on the viscosity desiredfor the particular coating method employed.

If, desired'the outer surface of the covering sheet may be and preferably isprovided with a waterproof coating 22 which may comprise a mixture of 10 parts nitrocellulose, 8 parts castor oil, 1 part dibutyl phthalate and a suitable solvent composition. This waterproof composition has some advantage and it does not adhere readily to the heated members by means of which the sealing of the'cap. to the container is carried out, but paraflin' or many other well known waterproofing materials or compositions may be used.

What we Eiaim is:

1. A package comprising a container formed of I cardboard or the like having on its outer surface 2. A package comprising a container formedofcardboard or the like having on-its outersurface a heavy coating of wax, and a tamper proof seal for the closure of said container, said seal comprising .a sheet of paper or the like provided on its package engaging side with a thin coating ofa zein thermoplastic immiscible with wax, the zein thermoplastic engaging the container through the wax and forming a tamper proof band between the sealing sheet and the material of the container.

a heavy coating of wax, and a tamper proof seal for the closure of said container, said seal comprising a sheet of paper or the like provided on itspackage engaging side with a thin coating of a zein thermoplastic immiscible with wax, the zein thermoplastic engaging the container through the wax and forming a bond between-the. sealing sheet and the material of the container having greater strength than the sealing sheetuorlthe material of the container.

3. A tamper proof seal for a cardboard or .like

container having a heavy coatingod wax on its outer surface, which comprises, a sheet of paper or the like provided. on. its container engaging surface with a thin coating ofa zein thermoor the like provided on its container engaging surfacewith a thin coating, of-a'zein thermoplastic immiscible with waxiwhich will become sufliciently tacky at the fl'owingtemperature of wax to form a bond between theysealing sheet and the material of the container havinggreater strength than theIsealing sheetor the material of the container, .under theapplication of pressureiat said temperature.

' GARRISON-HOUSEHOLDER.

WALTER V. SHEARER. 

